Selectively actuated well tool



June 8, 1965 W. G. OWNBY SELECTIVELY AGTUATED WELL TOOL Original Filed March 24. 1960 5 Sheets-Sheet 1 W. 6. Ownby INVENTOR.

ATTORNEY June 8, 1965 w G. OWNBY 3,187,815

SELECTIVELY ACTUATED WELL TOOL Original Filed March 24. 1960 5 Sheets-Sheet 2 W. 6'. 0 WI? 15 y INVENTOR.

ATTORNEY June 8, 1965 w. G. owNBY SELECTIVELY ACTUATED WELL TOOL 5 Sheets-Sheet 4 Original Filed March 24. 1960 VV. 6. Ownby INVENTOR.

BY Q C ATTO/P/VEV June 8, 1965 Original Filed March 24, 1960 W. G. OWNBY SELECTIVELY ACTUATED WELL TOOL 5 Sheets-Sheet 5 ATTORNEY Patented June 8, 1965 3,187,815 SELECEEVEZLY AJ'IUATEB WELL Tfif'L Warren G. fiwnhy, Houston, asst nor to amco incorporated, Houston, Tex., a corpora on of Texas firiginal application Mar. 2 5, 15 6i Ser. No. 17,385, new

Patent No. 3,195,543, dated Get. l, 1963. Divided and this application 31, 1963, Ser. No. 284,671.

8 @Claims. (Cl. led-63) This invention relates to subsurface well tools and more particularly to improved equipment including a device to be run down a well hole and to effect work automatically upon reaching a preselected dept-h location. This application is filed as a division of pending application Serial No. 17,385, now Patent No. 3,l( 5,548, filed March 24, 1960.

An object of the invention is to provide a well installation having at spaced apart predetermined depths a numer of signaling stations whose signals are distinctly different each from others, and a running tool having signal sensing means preset for responsive action when brought within the distinctive signal field of a selected station.

A further object of the invention is to provide an improved signal responsive assembly which discriminates between signaling stations and is influenced by the signal of a particular station for triggering a work performing operation into action.

Another object is to provide signaling stations having sets of adjacent co-operating permanent magnets arranged in the well tubing wall with the end poles of the sets respectively facing inwardly and of opposite polarity for the protrusion into the interior of the well tubing of magnetic lines of force as a concentrated field between the opposite polarity faces inwardly of adjacent magnets.

A still further object is to provide a group of signaling stations spaced apart downwardly in a well and each comprising .a set of spaced apart magnetic fields whose spacing differs from the spacing between the fields of other stations and a lowering tool having a stack of conductors spaced apart in relation to the spacing of the magnetic fields at the several stations whereby the conductors when combined in ditierent sets are spaced to match the field spacing of the stations respectively so that flow of current through any selected set of conductors and when the conductors of that selected set are concurrently within the magnetic fields of a given station, esults in voltage output concurrently at the conductors and influences relays for simultaneously closing series connected switches in a control circuit for thereby actuating a work performing mechanism.

Another object of the invention is to provide a work performing mechanism having an improved cartridge assembly for an explosive charge whose ignition gives an instantaneous buildup of high power energy to initiate a quick work action with force relief means timed into effect after a predetermined response of the mechanism.

Other objects and advantages will become apparent from the following specification having reference to the accompanying drawing illustrating a preferred but not necessarily the only embodiment of the invention and wherein FIGS. 1, 2 and 3 respectively show a tubing fragment in section with a running tool received therein in relatively diflerent relations; FIGS. 4A, 4B, 4C and 4D are complementary views partly in section showing on a large scale the co-operative relation of a running tool and a nipple coded to one another as they would be for a response of the working mechanism but showing the working mechanism still in its initial inactive relationship; FIG. 5 is a transverse section on line 55 of FIG. 433; FIG. 6 is a detail perspective VlBW of a sensing element and a pair of co-operat-ing pole pieces therefor; FIGS. 7, 8, 9 and 10 are fragmentary sectional views showing a pair of magnet carrying rings alternately positioned for providing fields ditterently spaced apart; FIG. 11 is a wiring diagram of an igniting circuit for an explosive charge and the controls therefor; and FIG. 12 is a detail sectional view of an improved explosive charge unit.

According to the invention, the usual well tubing string is made up at the time of installation in a well bore such as one which penetrates oil and gas sands, with any desired number of signaling stations at predetermined spaced apart depths and each station comprises a pair of separate magnetic fields protruding inwardly from the tubing in longitudinally spaced apart relation. Such longitudinal spacing between signaling fields differs at each station whereby a tool incorporating a pair of magnetic field responsive or signal sensing devices coded or matched to the twin fields of any given station can be run through the tubing string and only when its signal sensing devices are concurrently responsive to the selected stations traversed by the tool will they eliect an automatic actuation of a. work performing mechanism at the desired well depth location.

As magnetic field sensing elements, there is here proposed the use of small units of crystalline semiconductory compound of high carrier mobility and which when conducting electric current and upon being subjected to a magnetic field, respond to produce a Hall-elfect output voltage. Such output voltage produced at a pair of sensing elements at the same time is used to actuate electrical relays in controlling battery power for eiifccting work in a well. Semiconductors having high mobilities, such as the relatively new intermetallic compounds including indium antimonide and indium .arsenide, are suitable for sensing element use. Elements using indium antimonide are commercially available in the form of small thin wafers having four polarized electrical leads, two for current bias and two for Hall-output voltage. A number of the wafer elements can be suitably spaced apart in a compact stack which also includes a pair of pole pieces for each element and by electrical switching the elements of the multiple assembly can be made active two at a time in selected pairs physically spaced apart to correspond with magnetic field spacings of the tubing string stations. Accordingly, a running tool incorporating a stack of sensing elements can be preset for responsive vaction at any station selectively.

Signal transmission can be utilized for various well working operations and for convenience of disclosure the drawings illustrate positioning of a conventional fiuid flow control device including a hanger assembly to be latched in a tubing nipple. The hanger assembly has an outer tubular body 1 carrying annular packing rings 2 for sealing bearing on the interior surface of a well tubing string 3 and also having side windows to receive laterally movable latching dogs 4. Slidably fitted within the body 1 is a downwardly retractable hollow plunger 5 terminating upwardly in a spool-shaped fishing neck 6 and having in the region of the latch dogs 4 a stepped diameter portion providing in end to end succession an annular enlargement 7 above a smaller diameter zone 8. In its upwardly projected position of FIG. 4]), the plunger 5 presents its smaller diameter zone 8 in lateral alignment with the latch dogs 4 for the inward nonlatching retraction of the dogs but upon downward plunger travel at any time when the dogs are aligned with an internal annular keeper groove or notch 9 in a tubing nipple iii, the expander enlargement 7 moves behind and outwardly cams the latch dogs and then holds the dogs projected into latching reception within the keeper groove 9, as seen in FIGS. 2 and 3.

For running-in purposes, the lower tubular skirt 11 of a running tool as seen in FIG. 4t: is sleeved over the upper downward jar or hammer blow on top of the plunger causes the pin 12 to shear and pushes or depresses the plunger to its downward retracted position defined by stop abutment of a downwardly facing shoulder 14 on the upper end of the body 1 and also pushes the enlargement '7 into dog projected latching position within the keeper groove. With an explosive expansion furnishing the jar to effect plunger depression and latched securement of the tool hanger to the tubing string, the concurrent upward reaction on the running tool relative to the hanger shears thepin l3 and releases the running tool for free withdrawal from the well.

The latch setting downward jar on the plunger 5 occurs upon detonation of an explosive charge loaded in the running tool whenever the signal sensing elements are influenced upon their traverse of magnetic fields to which the elements are coded at a particular signal sending sta tion conveniently embodied in the keeper-groove containing nipple 1G. The length of the running tool with the hanger secured thereto is determined so that the longitudinal distance between the latch dogs 4 and the signal sensing elements is co-operatively related to or is substantially the same as the longitudinal spacing between the keeper groove 9 and the signaling fields for insuring latch dog and keeper groove alignment at the instant the plunger receives a downward jar as a consequence of signal response.

FIG. 1 shows the wire line suspended running tool in descent within a tubing string and with the latch dogs retracted and just above the keeper notch of a nipple. Considering thatthe signal sensing elements of the running tool are preset for simultaneous response to the magnetic fields of that particular nipple, then the response times detonation of the explosive charge and plunger retraction with outward projection of the latch dogs into the keeper notch aligned therewith, as seen in FIG. 2. FIG. 3 shows .the form of short bars having their magnetic axes disposed substantially radially and being grouped in spaced apart relations, both longitudinally and circularly of the nipple, to constitute four circular rows of magnets and with the magnets in the two lowermost rows and those in the two uppermost rows co-operating in each case in yielding a magnetic field by the fact that the inner ends of all magnets in each row are alike in polarity in relation, to one another but are unlike in polarity to the inner ends of all magnets in the other row of each of the two'pairs of rows.

At its upper end the nipple 10 is shown in FIG. 413 as being counterbored to receive a stack of rings held in place by split retainer ring 16 overlying the ring stack and snapfitted within an annular groove in the nipple wall. By mounting the rings within the counterbored pocket, a full open bore through the nipple is maintained for free passage of well working equipment. The ring stack includes two magnet carrying rings 17 of nonmagnetic material and a number, as, for example, six spacer rings 18 which, like the nipple it are of steel or other magnetic material and whose spacer length in the case of all but one ring is uniform for convenience of interchangeability and placement of selected numbers of rings above and below the upper nonmagnetic ring 17 in establishing desired spacing between the two magnet carrying nonmagnetic rings. Thus, if up to five signaling stations are to be located in a well hole, the tubing string is assembled with the desired number of nipples 10 for placement at predetermined depths and each will have a different spatial relationship to the two nonmagnetic rings 17 according to the disposition of the spacer rings 18. By way of illustration, FIGS. 4B, 7, 8, 9. and 10 show respectively one, two, three, four and five intervening rings 18 between the pair of magnet carrying rings 17.

Magnet carrying ring subassemlies are made up by first drilling radially through each nonmagnetic ring two spaced apart rows of circularly spaced apart holes and fitting thereto the bars 19 of permanent magnet material and of lengths corresponding to ring wall width. These bar inserts, with their end faces flush with the ring outer peripheral and inner surfaces, are then cemented or other.-

wise fixed in place and are charged magnetically to present the south seeking pole inwardly in the case of magnets in one circular row and the north seeking pole inwardly in the case of all magnets in the other row. When installed in a nipple, as in EEG. 4B, the radially spaced apart ends of each magnet in a'lower row will be opposite in polarity to the similarly positioned opposite ends of the magnets in the companion upper row. For example,.the outer faces of the upper row of magnets and the inner faces of,

the lower row of magnets in each ring 17 may be north poles and the remaining poles will be south seeking poles. The outermost north and south poles are isolated by the nonmagnetic ring and are joined through the nipple wall through their face cont-act therewith, while lines of force will protrude inwardly of the ring 17 between the inwardly facing north and south poles. Some lines of force will also extend downwardly around the bottom of the nonmagnetic ring and between north and south poles of the lower magnets, and similarly upwardly around the top of the nonmagnetic ring and between the north and south poles of the upper magnets but a major concentration of flux willextend between the inner faces of the upper and lower magnets. Two of such magnet carrying ring subasselnblies spaced apart provide twin spaced apart field patterns within the bore of the nipple and the relative spacing as controlled by the number of spacer rings 18 interposed between the magnet carrying rings marks the particular nipple as distinguished from other for signaling action of twin detectors of the running tool.

The running tool has its components housed within a long tubular body which for convenience of manufacture comprises a number of separately formed tubes threaded together in end to end succession. Each tube and any component housed therein consit'utes a subassembly unit and the several subassemblies-are axially aligned on a common iongitudinal center line about which adjoining subassernblies are rotatable for end to end screw threaded attachment. In addition to the lower tubular skirt 11, the housing includes a plug containing coupling portion 20, a tubular nonmagnetic section 21 enclosing a stack of signal sensing elements and, as seen in FIG. 4A, a coupling element 22, a tubular element 23 enclosing batteries, relays and switches electrically interconnected, as best seen in the FIG. 11 diagram, and a coupling'head 24 terminating upwardly in a threaded pin for connection to the end coupling joint of a conventional wire line.

At the thread carrying tubular portion of its upper end the lower skirt 11 provides an internal pocket 11a to receive an energy source or explosive shell assembly 25 which, as best seen in FIG. 12, encloses an explosive charge and is closed by a projectable disk or end plug 26. Immediately below the energy source 25, the central bore throughthe skirt 11 forms an expansible cylinder or variable volume chamber in co-operation with the projectable plug 26 and a slidable rod or plunger 27 fitted within the cylinder. In the initial position of these parts, the upper end of the plunger rod 27 engages with theprojectable plug 26 and at its lower end the rod has an enlarged head 28 in seating engagement with the latch expander plunger 6 of the hanger assembly. It follows that upon detonation of the explosive charge, the force of expanding gas is transmitted to and depresses the latch expander 6.

One or more later-ally projecting pins 29 on the side head 28 provide a key formation for vertical sliding reception and interlocking relations within an elongated slot 39 through the side wall of the skirt ll. Among other things, this elongated slot 3% accommodates fluid displacement from within the skirt 11 and incidently aiiords a large relier" opening for free escape of residual expanding gases at the end of the plunger stroke. More especially, gas relief immediately following projection of the plug 26 is by way of one or more chamber vent ports or openings 31 drilled radially through the cylinder wall at selected longitudinally spaced points in the travel range of the plug 26. Cartridge force and plug responsive travel determine initial energy build-up, its duration and cessation of pressure application. The side ports 31 are located for controlled gas escape and without its passage beside the plunger 27. They provide fast reduction and cessation of pressure application and minimize or prevent corrosive burning of the plunger and skirt bore surf-ace.

By controlling the size of the lateral openings 31, there will be a metered relief of pressure, which is of importance in controlling sudden application of downward force on the plunger rod, desirable for overcoming resistance to the start of movement, but with quick pressure relief after movement has been initiated for reducing force transmission when high energy application no longer is required.

The arrangement is of special importance Where fairly light work such as the setting of latches is involved, where the force required for first shearing the connector pin 12 exceeds the smaller push needed to start and shift the released latch expander plunger 5. High initial energy is immediately available for a sharp quick force application for releasing the expander plunger. Then follows an almost immediate gradual relief of expanding gas pres- Sure as the plunger is depressed and a final cessation of pressure application by complete gas escape at the end of the stroke to avoid destruction action. In other works, when the running tool is used for setting a light well device under low pressure, it provides a quick energy build-up whose peak energy duration is short. 6n the other hand, when a heavy well device is run in a deep, high-pressure and fluid-filled well, the same explosive unit and slide plunger and cylinder assembly still provides a quick energy build-up with peak energy maintained to overcome inertia of the massive parts and until they build up momentum and start on their way. Only thereafter is the projectile plug 26 moved sufficiently for releasing excess energy by venting pressure gas into the well bore.

An electrical coupling 32 mounted in the coupling portion 20 provides a detachable plug and socket connector on the longitudinal center line of the tool with the explosive charge unit for accommodating relative rotation of the connecting screw threads on the skirt l1 and the coupling portion 20. For that purpose, the bottom of the coupling 32 has an axially extended open socket at 32a concentric with the connecting screw threads of the cou pling portion 2%? and the socket slidably receives a plug or pin 51 of circular cross section projected upwardly from an insulator insert 52 in the top of the charge unit. At its upper end the coupling 32 has a plug and socket connection at 53 with a wiring connector 33 at the lower end of a stack of signal sensing units contained within the nonmagnetic tubular section 21. These sensing units include a number of spaced apart semiconductors 34- formed as disks or wafers, each sandwiched between and centrally clamped by oppositely projecting bosses 35 of a pair of disks of high magnetic permeability material providing spaced apart pole pieces 36 adapted for alignment with a set of co-operating magnets 19 whereby to extend a magnetic field between such magnets through the semiconductor which is between the particular pair of pole pieces 35. Conveniently, the assembly of detectors and pole pieces is held together by means of a series of three long tie rods 37 extending through equally spaced apart openings in the several pole pieces with enlarged heads at the lower ends of the rods 37 fitted in a bottom connector plate 33 clamped between opposing end faces on the coupling portion 2% and tubular section 21 and with screw threaded portions at the upper end of the rods threaded into an end coupling disk 39. Sleeved on the rods between neighboring pole pieces 36 are distance or spacer tubes 51. All spacer tubes, end plates and tie rods are of nonmagnetic material. Additional openings aligned with one another through the pole pieces 36 and the end clamping plates 38 and 3? permit the passage of a wire bundle by which the various parts are connected in the necessary circuitry system.

The wiring includes conductors for selectively placing each semiconductor 34 in circuit with a battery and for leading the Hall-sheet output voltage to relay switches in control of battery connections with the energy storing explosive charge unit. The batteries and the several relays are mounted within the tubular element 23, as is also a selector multiple switch unit havin an upwardly extending actuating shaft ail. Connected to this shaft 44 as by means of a polygonal pin and socket is the lower end of an actuating rod 41 cxtendin through the upper coupling 24 and having a terminal screw driver slot 4-2 through which the rod can be rotated for setting the selector switch unit.

The selector switch unit as diagrarnmed in PEG. 11 comprises the ganged switches SW1, SW2 andSWS, all shown in an off position and whose switch blades can be rotated together, each for engagement with any one of five active contacts. All of the contacts of switch SW1 are connected to the lowermost semiconductor for directing current therethrough from the battery B1. The five active contacts or" the switch SW2 are joined to the remaining five semiconductors so that as the switch blade engages any one of these switch contacts, a particular one of the semiconductors 34 will receive current from the battery B1. Whichever one of the semiconductors to which current ilow is directed through the selector switch SW2 will also be connected for output voltage led through the switch SW3 to the coil of a relay switch unit R2. A similar relay switch unit R1 has its coil connected to receive output voltage from the lowermost semiconductor 34 and when the switch blades of R1 and R2 are concurrently actuated by their respective coils, a circuit is closed from the battery B2 and through a relay switch unit R3. In other words, the relays Rll and R2 have their switch contacts in series relation with the battery B2 and the coil of the relay R3 and the relay R3 is actuated only at a time when relays R1 and R2 concurrently receive actuating voltage. When that does occur, the closing of the switch of the relay unit R3 directs current from the battery B3 to the connector C for the explosive squib for igniting the explosive charge.

From the above it will be seen that the lowermost semiconductor of the stack may be combined with any one of the remaining semiconductors to provide a pair of signal sensing units which are capable of discriminating between signaling stations and to have no effect on the main control circuit unless the pole pieces for the sensing elements selected by the presettiug of the selector switch simultaneously come into the influences of the twin signal ing fields of a signaling station. It, for example, the sensing element next above the lowermost element has been selected, then when the two sets of pole pieces come into substantial alignment with the inwardly facing north and south poles of the two sets of magnets, as shown in FIG. 4, the output voltage would effect the simultaneous closing of the series connected switches of the relay units Rll and R2 for triggering ignition of the explosive charge. On the other hand, if the selector switch has brought the topmost semiconductor into current flow relation with the battery Bl, hen the position of the parts in PK would influence only the bottom semiconductor for actuating the relay R1 which would be ineffective inasmuch as the relay R2 at that time is ineffective and both relays would be actuated only when the running tool traverses a nipple whose spacing of the magnets, as seen in FIG. 10, matches that of the semiconductors selected for response to spaced apart fields, as in FIG. 10. Likewise, the se-' lector switch can set the signal sensing units for co-action in pairs in matched relation to the field settings indicated in FIGS. 7, 8 and 9.

The electrically detonated explosive type energy source 25 is a specially designed assembly including an outer cartridge or shell i whose outside diameter throughout its major extent is cylindrical and has a lower downwardly tapering portion 43. This outside configuration conforms to the internal shape at the upper end of the body skirt 11 to permit easy insertion and withdrawal, as well as the properly located and sealed fitment of the parts. Additionally, for sealing against blow-by of expanding gases, the cartridge 5t near its upper end has an annular groove to receive an O-ring 4-4 for bearing engagement with the interior surface of the body skirt 11. The cartridge is a cup-shaped case and centrally disposed within the chamber 54 of the case is a tubular primer or electric squib 45 having conductors extending through the closed end or base 55 of the case for detachable plug connection with the bulkhead feed-through coupling 32. Surrounding the squib t5 and filling the chamber space are a backfill body 46 adjacent the closed end and an explosive charge 47'held near the open end by the projectable plug 26 closely fitted interiorly of the open end and preferably sealed by an O-ring 48 carried within an annular groove in the closure plug 26. The electric squib acts to detonate the explosive charge which supplies expanding energy gas for the working operation. The backiill body 46 is a ring of moisturenon absorbing sealing material and comprises an epoxy resin plus a suitable curing agent and a filler such as plaster of Paris. It guards against excessive gas blow-back and prevents damage to the chamber and the bulkhead feedthrough coupling. The relative amounts of epoxy compound backfill 46 and explosive powder 47 are carefully selected and accurately metered so that after the charge is tamped into place there will be no void when the closure plug 2d is set in place. To prevent contamination of the explosive charge by volatile liquids and gases such as those in which it may become submersed, it is here proposed to employ special precautions in final assembly of the cartridge. These include thorough cleaning of all components, includinga cleaning operation after the epoxy fill has been set and cured. it should be here mentioned that fillers employing solvents and requiring their evolvement for hardening should be avoided and instead suitable epoxy compounds have been selected with careful compounding and treatment for insuring that the curing agent is fully reacted without any contaminating remainder. In the final step of setting the plug 26 over the explosive charge, the assembly is placed in a vacuum chamber or hell jar with the cap just resting on the powder charge, whereupon the production of vacuum to match the signal of a particular nipple andthat the tool will safely pass thnoughother coded nipples regardless of the speed of tool travel, and which enables a fast running operation with assurance of proper response at the selected depth location.

- While the invention has been described with reference to a particular detail embodiment, its scope is not to be limited other than set forth in the appended claims.

What is claimed is: ll. An explosive unit comprising a cup shaped cartridge having a base and an open ended chamber projected space within the chamber near the base thereof and sealably embracing the peripheral surface of the primer, and

a projectile plug inserted within the open end of the chamber, a sealing ring carried by the plug in sealing engagementwith the chamber wall and an explosive charge behind the plug and filling the remainder of the chamber space.

2. In a well tool of the character described, a housing to be'passaged through a well and provided with an axially extended cylinder, a motion transmitting plunger slidably mounted within the cylinder for travel through a given range and initially located at one end of the travel range, a cartridge mounted in the cylinder in tandem relation with said plunger and formed with an open ended chamber whose open end is adjacent said plunger, a projectile plug slidably fitted within the open end of the chamber for projection therefrom into pressure imparting abutment with the plunger to effect plunger slide travel, a moisture nonabsorbent plastic material occupying the chamber adjacent the base thereof, a primer projected from the base and through said plastic material, an explosive charge packed between said plasticmaterial and the projectile plug and active upon ignition to project the latter and metered venting means leading from the cylinder beyond said plug in the initial location of the same and adapted to be passed by the plug upon its travel away from said initial location to thereby vent the cylinder.

3. In combination, a pair of running tool subassemblies arranged in end to end succession, rotatable attachment means joining the adjacent ends of said subassernblies with their longitudinal center lines in alignment, a force transmitting plunger slidably mounted in one of the subassemblies for force transmitting travel in a direction away from said adjacent ends, an electrically energized force charge unit pocketed in said one of the subassemblies between the end thereof and said plunger, electric current supply means carried by the other subassembly and a pair of detachable electrical connectors for delivery of current from said supply means to the charge unit and comprised of axially detachably engageable socket and pin members, one fixed as a part of the charge unit and the other fixed as a part of said other subassembly and both located on said longitudinal center lineof the subassemblies and relatively rotatable for accommodating rotative action of said attachment means.

4. As a subcombination unit of a well running tool having a tubular housing containing means to supply current to one element of a pin and socket type connection atone end of the housing, said subcombination unit including a detachable housing skirt extension having means at one end for rotatable attachment with the housing and also having therein an internal pocket at said end, an explosive charge containing shell fitted to said pocket and provided with one element of a pin and socket type connection, said one element projecting'coaxi-ally of the rotational axis of the attachment means aforesaid and affording a current conductor to the explosive charge of current for firing the charge, and a plunger member slidably mounted within the skirt extension to receive and transmit force from a fired explosive charge contained in the shell. r

5; In a running tool for co-operation with a well tubing in the setting of a latch unit in the tubing, upper and lower tubular housings, means detachably attaching the housings in end to end succession and being connectable and disconnectable upon relative housing rotation about a longitudinal axis, co-operating pin and socket electrical connectors carried one by the upper housing and the other by the lower housing for longitudinal sliding fitment and relative rotation about said longitudinal axis, means within the upper housing supplying current to said connectors, an explosive charge containing shell fitted Within the lower housing and provided with an electrical igniter connected with the connector carried by the lower housing, means at the lower end of the lower housing for detachably mounting a latch unit which is to be set by iorce supplied by the shell contained explosive charge and a plunger slidably mounted in the lower housing in the region between the last mentioned means and the explosive charge containing shell for the transmission of latch setting force.

6. Means to constitute a lower subassembly of a running tool and to be detachably connect-able at its upper end with another running tool subassembly, said means including a tubular housing, means at the lower end of the housing for detachable connection with a latch unit to be set in a Well tubing string, an explosive char-ge receiving pocket in the housing in spaced relation to and above the latch unit connecting means, a force transmitting plunger slidably fitted in the housing between said pocket and said connecting means and interengageable surfaces on the plunger and the housing defining upper and lower limits of plunger slide travel, said housing having force venting means extending through the housing wall in position to be covered by an adjoining portion of the plunger at its uppermost limit and to be uncovered upon plunger descent.

7. In a latch carrying and force applying sub-assembly of .a running tool, a housing having connector means at its lower end for a latch unit to the set in a well tubing, a force transmitting member slldably mounted in the housing above said connector means, tubular attachment means at the upper end of the housing for its detachable connection in end to end succession with another running tool subassembly, said housing at its upper end having an internal shell receiving bore concentric with said tubular attachment means and extending as an upper open-ended pocket of substantially uniform and relatively large diameter for a portion of its longitudinal l dimension and a downwardly tapered seat below the uniform diameter portion, a shell insertable end-wise through said open end and shaped exterior-1y in matched relation to the bore for downward bearing on said tapered seat, a detonator fitted within the shell and provided :with an upwardly protruded electrical pin connector externally of and coaxially related to the upper end of the shell, an explosive charge filling the shell around the detonator and a charge retaining pnojectable closure plug in the bottom of the shell.

8. In an electrically ignited combustible force producing unit for fitment to a chamber in a well tool, a cupshaped shell, an electrical connector plug mounted on the base of the cup-shaped shell to project therefrom on the longitudinal center line of the shell, a detonator housed in the shell and provided with a pair of current conductor leads of which one is grounded on the shell and the other is electrically connected with said connector plug, a force transmitting projectable plug closing the open end of the shell and peripherally sealed therewith, a body of moisture resistant plastic contained within the shell in close fitting engagement with adjacent opposing surfaces of the shell and the portion of the detonator adjacent said base as a mounting attachment and sealant between said sunfaws and a charge of combustible material packed around the detonator below said body and filling the shell between the body and said plug.

References Cited by the Examiner UNITED STATES PATENTS 2,328,308 8/43 Turechek 166-55 .5 2,3 62,7 3 8 1 1/44- Yarb-rou-gh 16655 .5 2,649,736 8/ 53 Phillips 1-6 6-55 .5 X 2,815,817 10/57 Conrad 166-181 X 2,821,136 1/58 C-a-stel 16655.5 X 2,926,638 3/ 60 Mangus et a1 .891.01 X 3,024,843 3 [6-2 Hane-s l6 663 3,059,576 10/ 62 Haefner 10228 OTHER REFERENCES A.P.C. Application of Schlumberger, Serial No. 271,524, published May 25, 1943.

CHARLES E. OCONNELL, Primary Examiner. 

4. AS A SUBCOMBINATION UNIT OF A WELL RUNNING TOOL HAVING A TUBULAR HOUSING CONTAINING MEANS TO SUPPLY CURRENT TO ONE ELEMENT OF A PIN AND SOCKET TYPE CONNECTION AT ONE END OF THE HOUSING, SAID SUBCOMBINATION UNIT INCLUDING A DETACHABLE HOUSING SKIRT EXTENSION HAVING MEANS AT ONE END FOR ROTATABLE ATTACHMENT WITH THE HOUSING AND ALSO HAVING THEREIN AN INTERNAL POCKET AT SAID END, AN EXPLOSIVE CHARGE CONTAINING SHELL FITTED TO SAID POCKET AND PROVIDED WITH ONE ELEMENT OF A PIN AND SOCKET TYPE CONNECTION, SAID ONE ELEMENT PROJECTING COAXIALLY OF THE ROTATIONAL AXIS OF THE ATTACHMENT MEANS AFORESAID AND AFFORDING A CURRENT CONDUCTOR TO THE EXPLOSIVE CHARGE OF CURRENT FOR FIRING THE CHARGE, AND A PLUNGER MEMBER SLIDABLY MOUNTED WITHIN THE SKIRT EXTENSION TO RECEIVE AND 